Novel cardenolides and derivatives



United States Patent NOVEL CARDENOLIDES AND DERIVATIVES Yvon Lefebvre, Pierrefonds, Quebec, and Jean-Marie Ferland, Montreal, Quebec, Canada, assignors to American Home Products Corporation, New York, N.Y., a corporation of Delaware No Drawing. Filed May 24, 1966, Ser. No. 552,389

17 Claims. (Cl. 260-2105) ABSTRACT OF THE DISCLOSURE Novel cardenolides of the general formula R1 M \I ll wherein R represents hydrogen or hydroxyl, R represents two atoms of hydrogen or oxygen, R is hydrogen, a lower aliphatic acyl group containing from two to four carbon atoms or the glucoside residue. The compounds have cardiotonic and mineralocorticoid activity and dosage forms thereof are disclosed. Also disclosed is a process for making the new compounds starting with 17,8-[3-furyl]-substituted androstanes.

VT Y: 0 R1 I L, 1 I OH R-O R I. OH Ia.

The products of this invention have cardiotonic and mineralocorticoid activity. They may be administered orally in the form of tablets or capsules containing from 1 to mg. of the active ingredients each, or by injection in the form of sterile solutions or suspensions in pharmacologically acceptable vehicles containing from 1 to 10 mg. of the active ingredients per dosage unit.

The novel cardenolides of this invention of Formula I are prepared by treating l7fi-[3'-furyl]-substituted androstane derivatives of Formula II in which R represents hydrogen or hydroxyl, -R represents two atoms of hydrogen, the ethylenedioxy group, or oxygen, and R "ice represents a lower aliphatic acyl group, with an N-haloimide or N-haloamide, such as, for example, N-bromosuccinimide, or N-chloroacetamide, or with a hypohalous acid, such as, for example, hypochlorous acid, isolating the reaction product by extraction with a water-immiscible solvent, and purifying it, for example, by chromatography or crystallization. The 3-acyl group of the compounds of Formula I thus obtained may be hydrolyzed to obtain the corresponding 3,8-hydroxylated compounds of Formula I, which may in turn be etherified with suitable glucose or hexose derivatives to yield the corresponding 3fl-glucosides, or 35-hexosides as occurring in natural glycosides.

More specifically, we prefer to use as starting materials for the preparation of the novel cardenolides of this invention certain 17fl-[3'-furyl]-substituted derivatives of androstane of Formula II in which R represents hydrogen or hydroxyl, R represents two atoms of hydrogen or the ethylenedioxy group or oxygen, and R represents a lower aliphatic acyl group, such as, for example, the acetyl, propionyl or butyryl group. These compounds may be prepared by the method described by Minato and Nagasaki in Chemistry and Industry, 1965, p. 899, viz, by reduction with diisobutyl aluminium hydride of the appropriate cardenolides of Formula III in which R represents hydrogen or hydroxyl, R represents two atoms of hydrogen or the ethylenedioxy group, and R represents hydrogen, to obtain the corresponding |17/8-[3'- furyl]-substituted androstane derivative of Formula II in which R, R and R are as defined above. During the course of this reduction it is necessary to protect certain reactive groups such as, for example, the aldehyde group of strophanthidin of Formula II in which R represents hydroxyl, R represents oxygen and R represents hydrogen. Such temporary protection is advantageously afforded, for example, by the ethylenedioxy group which may be easily introduced by reacting the compound containing a reactive oxo group with ethylene glycol in the presence of a small amount of p-toluenesulfonic acid, and said protective ethylenedioxy group may be readily removed after completion of the reduction by subjecting the ethylenedioxy-substituted compound to hydrolysis with dilute hydrochloric acid in acetone solution as described by Lingner et al. in Arzneimittelforschung, vol. 13, p. 142 (1963).

The preferred starting materials of Formula -II in which R represents hydrogen, obtained as described above, are then acylated by treating them with the appropriate lower aliphatic acid anhydrides or acyl chlorides in pyridine solution.

The 3-acylated-175-[3'-fury1]-substituted androstane derivatives of Formula II in which R represents hydrogen or hydroxyl, R represents two atoms of hydro-gen, the ethylenedioxy group, or oxygen, and R represents a lower aliphatic acyl group, obtained as above, are then treated with a reagent which furnishes the elements of a hypohalous acid, such as, hypochlorous or hypobromous acid, upon contact with water. Preferred reagents for this reaction are certain N-haloimides, or N-haloamides, such as, N-chloroor N-bromo-succinimide or N-chloro or N-bromo-acetami-de, used with or without small amounts of perchloric acid. Water must be present, and preferred organic solvents include aliphatic and cyclic ethers, such as, for example diethyl ether, dioxan or tetrahydrofuran; lower aliphatic ketones such as, for example, acetone or methyl ethyl ketone; aromatic hydrocarbons, such as, for example, benzene, toluene, or xylene; lower aliphatic esters, such as, for example, the lower alkyl acetates; lower aliphatic carboxylic acids, such as, for example, acetic or tbutyric acid; lower aliphatic halogenated hydrocarbons such as, for example, chloroform, methylene chloride, or ethylene dichloride; and lower aliphatic tertiary alcohols such as, for example, t-butanol. Primary and secondary alcohols are not operative and must be excluded. The time of reaction may extend from five minutes to twenty-four hours, and reaction conditions are preferably chosen so as to complete the reaction within one half hour. The temperature range at which the reactions may be carried out is from. 50 C., with temperatures of about -30 C. being the preferred range. The reaction product is isolated by extraction with a water-immiscible solvent, preferably with ether, washing with water or saturated sodium chloride solution, drying, and evaporating the solvent. The residue is purified by chromatography or by crystallization to yield the desired 23-desoxo-21-oxo-card-20(22)-en0lide of Formula I in which R, and R are as defined above, and R represents two atoms of hydrogen or oxygen.

The above reagent capable of furnishing the elements of a hypohalous acid is employed in substantially equimolar amounts. When two moles of reagent per mole of steroid are used, an intermediate halogenated ketone of Formula IV in which R, R and R are as defined above and X rep-resents chlorine or bromine is obtained. The latter product may be reduced to the corresponding lactone of Formula I by treatment with zinc in acetic acid.

Alternatively, the same compounds of Formula I are also obtained by treating the starting material, the 3-acylated-17;8-[3'-fury1]-substituted androstane derivative of Formula II in which R, and R are as defined above, and R represents two atoms of hydrogen, the ethylenedioxy group, or oxygen, with substantially equimolar amounts, of a hypohalous acid, preferably hypochlorous or hypobromous acid, under the same conditions as described above, and working up in a similar manner.

When two moles of hypohalous acid per mole of steroid are employed, the intermediate of Formula IV is obtained as above, and may be reduced to the corresponding compound of Formula I as described above.

The above process is generally applicable to l7-[3'- furylI-substituted steroids of the androstane and estrane series, provided the latter compounds do not contain unprotected primary or secondary alcohol groups or unprotected isolated double bonds.

Such alcohol functions may be protected by esterification or etherification. Isolated double bonds are best protected by bromination.

In its most general form, the reaction may be described by the following formulae, in which St represents a steroids nucleus of the estrane and androstane series with the characteristics cited above attached in position 17 to the furan nucleus, and X represents chlorine or bromine.

As described above, the use of substantially one molar equivalent of N-haloimide or N-haloamide or hypohalous acid per mole of steroid will lead directly from the 17-[3'-furyl]-substituted steroid of Formula Ila to the corresponding lactone of Formula Ia. When substantially two moles of H-haloimide or N-haloarnide or hypohalous acid per mole of steroid are used, the intermediate halolactone of Formula Na in which X represents a halogen atom is being obtained, and the latter compound may be reduced with zinc and acetic acid to the lactone of Formula Ia, as described above.

St St E J 01 i Ha. Ia.

The 23-desoxo-2l-oxo-card-ZO(22)-enolides of Formula I in which R, R and R are as defined above, obtained as described above, may then be subjected to alkaline hydrolysis, preferably with potassium carbonate in aqueous methanol, to yield the corresponding 3fl-hydroxy-23-desozo-21-oxo-card-20(22)-enolides of Formula I in which R and R are as defined above, and R represents hydrogen.

Furthermore, the 23-desoxo-21-oxo-eard-20 (22)-enolides of Formula I in which R represents hydrogen or hydroxyl, R represents two atoms of hydrogen or oxygen and R represents hydrogen, obtained as above, may then be converted to their corresponding 3fl-glucosides or 3/8- hexosides by reacting them with suitable hexose derivatives, such as, for example, with acetobromoglucose, preferably in dioxan solution, and in the presence of silver oxide and magnesium sulfate, as described by Elderfield et al. in J. Am. Chem. Soc., vol. 69, p. 2235 (1947) or in ethylene dichloride with silver carbonate as described by Zorbach et al. in J. Med. Chem, vol. 6, p. 298 (1963). In this manner when using, for example, acetobromoglucose, there are obtained the corresponding Zip-tetraacetyl-d-glucosides of the above 23-desoxo-21-oxo-card- 20(22)-enolides of Formula I in which R and R are as defined above, and R represents the tetraacetylglucosyl group. The latter compounds may then be deacetylated, preferably with barium methoxide as described by Elderfield et al. cited above, to obtain the corresponding 35-dglucosides of the 23-desoxo-2l-oxo-card-20(22)-enolides of Formula I in which R and R are as defined above, and R represents a d-glucosyl group.

The following formulae and examples in which R, R and R are as defined above, will illustrate this invention.

l T'l A 25.5% solution of diisobutyl aluminum hydride in dry tetrahydrofuran (72 ml.) is added dropwise to a solution of digitoxigenin .(15 g.) in tetrahydrofuran (200 ml.) at a temperature between 20 and -25 C. in an atmosphere of nitrogen. The reaction mixture is stirred for an additional 20 minutes at the same temperature. A 10% aqueous sulfuric acid solution (50 ml.) is added and the mixture is poured into an aqueous 5% sodium bicarbonate solution. After filtering through celite, the mixture is extracted with ether. The ether extract is washed with water, dried 'and evaporated to dryness leaving crude 17,3-[3-furyl]-androstane-3B,14,B-diol, purified by crystallization from methylene chloride-ether to M.P. 201- 203 C.

Similarly, periplogenin yields upon reduction 17(3-[3'- furyl]-androstane-3 8,5;3,14 8-tri0l.

In a similar manner, the 19-ethylenedioxy derivative of strophanthidin yields 19 ethylenedioxy 1713 [3'-furyl]- androstane-3 3,5 3,14fi-triol when reduced with diisobutyl aluminum hydride. Upon treatment with 0.1 N hydrochloric acid in acetone solution the latter compound is hydrolyzed to 17p [3'-fury1]318,55,l4B-trihydroxyandrostan- Example 2 g.) obtained as described in Example 1, pyridine (50 ml.) and acetic anhydride ml.) is allowed to stand at room temperature overnight. Methanol (25 ml.) is added and the solution is poured into ice-water and ether extracted. The ether is washed with dilute sulfuric acid, sodium bicarbonate and water. After drying and evaporating the solvent the crude acetate is crystallized from aqueous methanol to yield pure 3 ,B-acetoxy-17 ,8-[3-fury1]- 5/3-androstan-14B-ol, M.P. 155-157 C. Similarly, acetylation of 17,9-[3'-furyl]-androstane-3,3,5fi,14,3-triol and 17fl-[3'-fu'ry1]8 8,55,14fl-trihydroxyandrostan-19-a1 yields the corresponding 3,3-acetoxy-l7fl-[3'-furyl]-androstanc- 53,145 diol and 3,9 acetoxy 5,8,14fi-dihydroxy-1-7fl-[3- furyl]-androstan-l9-al, respectively.

Example 3 By a similar procedure as described in Example 2, acylation with the appropriate acid anhydrides or acyl chlorides such as, for example, propionic anhydride or butyryl chloride of 17,3-[3'-furyl]-5fi androstane-3fi,14fldiol, 17B-[3-furyl]androstane-3;8,5fi,14B-trio1 and 17B-[3'- furyl]65,5 3,14fl-trihydroxyandrostan-19-al yields the corresponding 3-acy1ates, 3fl-propionyloxy or 3B-butyryloxy- 17,8-[3'-furyl]-5,B-androstan-19fi-ol, or 3fl-propionyloxy or 3,8 butyryloxy 17 8-[3'-furyl]-androstane-5B,14fi-diol or 3fl-propionyloxyor 3fi-butyry1oxy-17/3-[3-furyl] -5;3,14fidihydroxyandrostan-19-al, respectively.

Example 4 N-bromosuccinimide (900 mg.) is added portionwise to a stirred solution of 35-acet0xy-17fi-[3'-furyl]-5,B-androstan-14fi-ol (2 g.) in dioxane (100 ml.) and water (8 ml.), and the reaction is allowed to proceed for minutes at room temperature. The solution is diluted with water and ether extracted. The ether extracts are washed with water, dried and evaporated. The residue is chromatographed on silica gel, and the fractions eluted with benzene-ether (3:1) are combined and crystallized from mixtures of methylene chloride-ether to yield pure 3}?- acetoxy 23 desoxo-14-hydroxy-2l-oxo-Sfi-card-ZO(22)- enolide M.P. 172173 C. Similarly, 3fi-acetoxy-17fi-[3'- furyl]-androstane-5,3,1413-diol and 3fi-acetoxy-5/L14fl-dihydroxy-17,6-[3'-furyl] -androstan-19-al yield, respectively, acetoxy 23 desoxo 5 8,14 dihydroxy-Zl-oxocard- 20(22) enolide and 3,8 acetoxy 23 desoxo-53,14-dihydroxy 19,21 dioxocard-20(22)-enolide when treated with N-bromosuccinimide.

The same products as described above are also obtained when using equivalent amounts of N-chlorosuccinimide instead of N-bromosuccinimide, and allowing the reaction to proceed as above for approximately five hours.

Alternatively, the same compounds as described above are also obtained when adding 0.8 ml. of water and 0.04 ml. of glacial acetic acid to a solution of 200 mg. of the same starting materials as described above, then adding dropwise an aqueous solution of sodium hypochlorite (1.44 M, 0.5 ml.), stirring at room temperature for approximately one hour, and working up as described above.

6 Example 5 In the same manner as described in Example 4, the 3- acylates such as the 3-propionates and 3-butyrates of 1713- [3' furyl] 5B androstane 35,14,8-diol, 17 3-[3-furyl]- androstane-3B,5fl,14/8-triol and 17/3-[3'-furyl]-3/3,5;3,14[3- trihydroxyandrostan-19-al are treated with N-bromosuccinimide to yield the 3-acylates, such as, for example, the 3-propionates and 3-butyrates of 23-desoxo-3B,14-dihydroxy 21 oxo-5fi-card-20(22)-enolide, 23-desoxo-21- 0x0 3,19,53,14 trihydroxycard 20(22) enolide and 23- desoxo 19,21 dioxo 3,8,55,14-trihydroxycard-20(22)- enolide, respectively.

Example 6 A solution of 3/3-acetoxy-23-desoxo-14-hydroxy-2l-oxo- 5fl-card-20(22)-enolide (200 mg.), potassium carbonate (200 mg.) methanol (8 ml.) and water (2 ml.) is refluxed for two hours. After cooling, the solution is acidified with acetic acid, diluted with water and extracted with a mixture of methylene chloride and ethyl acetate. The organic solvents are washed with water, dried, and evaporated, yielding 23 desoxo 318,14 dihydroxy 21 oxo-Sfi-card- 20(22)-enolide, characterized by infrared absorption bands at 3595 cmr 1745 cmr and 1645 cm.- Similarly, 313 acetoxy-23-desoxo-5fi,14-dihydroxy-21-oxocard- 20(22) enolide and 3,8 acetoxy 23 desoxo 5,6,14-dihydroxy-19-21-dioxocard-20(22)-eno1ide are hydrolyzed to yield, respectively, 23-desoxo-21-oxo-3/3,5B,14-trihydroxycard 20( 22) enolide and 23 desoxo-19,21-dioxo- 3,8,5B,l4-trihydroxycard-20(22)-eno1ide.

In a similar manner, the 3-propionates and 3-butyrates of 23 desoxo 3,8,14 dihydroxy-21-oxo-5,B-card-20(22)- enolide, 23 desoxo 21 0x0 3 {3,5 {3,14 trihydroxycard- 20(22) enolide and 23 desoxo-19,21-dioxo-3;8,5B,l4-trihydroxycard-20(22)-enolide obtained as described in Example 5, yield upon hydrolysis 23 desoxo 3,8,14 dihydroxy 21 oxo-5fi-card-20(22)-enolide, 23-desoxo-2l- 0x0 35,55,14 trihydroxycard 20(22) enolide, and 23- desoxo 19,21 dioxo 35,55,14 trihydroxycard-20(22)- enolide, respectively.

Example 7 23 desoxo-3 3,l4-dihydroxy-21-oxo-5fl-20(22)-enolide (375 mg.) obtained as described in Example 6, dissolved in 10 ml. dry dioxan, is stirred at room temperature with 500 mg. dry silver oxide and 1 g. anhydrous magnesium sulfate. A solution of 820 mg. acetobromoglucose is added over a period of one hour, and stirring is continued for 24 hours at room temperature. After working up as described by Elderfield et a1. cited above, 23-desoxo-3fi,14- dihydroxy 21 0x0 5fi-card-20(22)-enolide-3-B-d-tetraacetyl-glucoside is obtained.

In the same manner, but using 23 desoxo 21 oxo- 3,9,55,14 trihydroxycard 20( 22) enolide or 23-desoxo- 19,21 3fi,5;8,14 trihydroxycard 20(22) enolide instead of 23 desoxo 318,14 dihydroxy 21 oxo-Sp-card- 20(22)-enolide, the corresponding tetraacetyl-B-d-glucosides, viz, 23 desoxo 21 oxo-3/3,5 3-14-trihydroxycard- 20(22)-enolide-3-,B-d-tetraacetyl-g1ucoside and 23-desoxo- 19,21 dioxo 35,513,14 trihydroxycard-20(22)-en0lide- 3 8-d-tetraacetyl-glucoside, are respectively obtained.

By hydrolysis of the 3-fi-d-tetraacetyl-glucosides obtained above, in dry methanol with approximately 0.05 N barium methoxide following the procedure described by Elderfield et al., cited above, 23-desoxo-3B,14-dihydroxy- 21 0x0 5B card 20(22) enolide 3-B-d-glucoside, 23- desoxo 21-oxo-3;8,5fl,l4-trihydroxy-card-20(22)-enolide- 3- 3-d-glucoside, and 23-desox0-19,21-diox0-3B,5fi,14-trihydroxycard 20(22) enolide-3-fi-d-glucoside are respectively obtained.

Example 8 To 3 3-acetoxy-l7fl-[3-furyl]-5[ -androstan-14-ol, obtained as described in Example 2 (0.200 g.) in dioxan (10 ml.), and water (0.8 ml.), is added portionwise N-bromosuccinimide (0.180 g), and the mixture is stirred at room temperature for one-half hour. The solution is diluted with ether, washed with saturated sodium chloride solution, dried and evaporated. The oily residue contains 3,8-acetoxy-23-bromo-14-hydroxy-23-desoxo-21 oxo 513- cardenolide, characterized by NMR spectroscopy with characteristic peaks at 6.91 p.p.m. and 7.18 ppm.

The above oily residue is stirred in acetic acid (20 ml.), with zinc (2.2 g.), for a period of one-half hour. The zinc powder is then removed by filtration and the filtrate diluted with chloroform. The organic layer is washed with water till neutral, dried, and evaporated, to leave 313-acetoxy-14-hydroxy-23-desoxo-2l-oxo-Sfi cardenolide, identical with the product described in Example 4.

In the same manner, but using N-chlorosuccinimide instead of N-bromosuccinimide, 3 fi-acetoXy-23-chloro-14- hydroxy-23-desoxo-21 oxo 5B cardenolide is obtained from which 3B-acetoxy-14-hydroxy-23-desoxo-21-oxo-5[3- ca'rdenolide is obtained in the same manner as described above.

We claim:

1. A compound of the formula wherein R is selected from the group which consists of hydrogen and hydroxyl; R is selected from the group which consist-s of two atoms of hydrogen and oxygen; and R is selected from the group which consists of hydrogen, lower aliphatic acyl groups containing from two to four carbon atoms and the glucoside residue.

2. 3B acetoxy 23 desoxo 14 hydroxy 21 oxo- 5B-card-20(22)-enolide, as claimed in claim 1.

3. 3B acetoxy 23 desoxo 55,14 dihydroxy 21- oxocard-20(22)-enolide, as claimed in claim 1.

4. 3B acetoxy 23 desoxo 5 8,14 dihydroxy 19,21- dixocard-20(22)-enolide, as claimed in claim 1.

5. 23 desoxo 35,14 dihydroxy 21 oxo 513 card- 20(22)-enolide, as claimed in claim 1.

6. 23 desoxo 21 oxo 35,56,14 trihydroxycard- 20(22)-enolide, as claimed in claim 1.

7. 23 desoxo 19,21 dioxo 35,55,14 trihydroxycard-20(22)-enolide, as claimed in claim 1.

8. 23 desoxo 3,8,14 dihydroxy 21 oxo B card- 20(22)-enolide 3-B-d-tetraacetyl-glucoside, as claimed in claim 1.

9. 23 desoxo 21 0x0 3fi,5(3,14 trihydroxycard- 20(22)-enolide 3-fi-d-tetraacetyl-glucoside, as claimed in claim 1.

10. 23 desoxo 19,21 dioxo 35,55,14 trihydroxycard 20(22) enolide 3 p d tetraacetyl-glucoside, as claimed in claim 1.

11. 23 desoxo 35,14 dihydroxy 21 oxo-SB-card- 20(22)-enolide 3-fi-d-gluc0side, as claimed in claim 1.

12. 23 desoxo 21 oxo -3,8,5,B,l4-trihydroxycard- 20(22)-enolide 3- 8-d-glucoside, as claimed in claim 1.

13. 23 desoxo 19,21 dioxo 3fl,5fi,14 trihydroxycard 20(22) enolide 3 p d glucoside, as claimed in claim 1.

14. 35 acetoxy 23 bromo 14 hydroxy-23-desoxo- 21-oxo-5fi-cardenolide.

15. The process which comprises treating a compound of the formula in which R, R have the above-defined significance and R is selected from the group consisting of two atoms of hydrogen and oxygen.

16. The process which comprises treating a compound of the formula i t? V wherein R is selected from the group consisting of hydrogen and hydroxyl; R is selected from the group consisting of two hydrogen atoms, ethylenedioxy, and the oxo group; and R represents a lower aliphatic acyl group with substantially two molar equivalents of a reagent selected from the group which consists of N-haloimides,

N-haloamides and hypohalous acids, thereby obtaining a N-haloamides and hypohalous acids, thereby obtaining a compound of the formula compound of the formula H I OH R20 wherein R and R have the significance above defined, R is selected from the group consisting of two atoms of hydrogen and oxygen, and X is selected from the group .wherem R and R2 have the slgmfifzapce above defined R1 which consists of chlorine and bromine, and dehalogenat- 18 selected from the group consisting of two atoms of ing the latter compound with zinc and acetic acid to obhydrogen and oxygen, and X is selected from the group 20 t a co 0 nd fth form 1 which consists of clilorine and bromine. a1 mp u o e u a 17. The process which comprises treating a compound --0 of the formula V OH in which R, R and R2 have the significance defined above. R 0

References Cited UNITED STATES PATENTS wherein R is selected from the group consisting of hy- 40 2,968,596 1/1961 Master 260 23 drogen and hydroxyl; R is selected from the group con- 3,177,200 4/1965 Meyer 260-2105 Sisting of two hydrogen atoms ethylenedioxy and the 3,211,719 10/ 1965 Von Wartburg 6! a1. 260-2105 0x0 group; and R represents a lower aliphatic acyl group with substantially two molar equivalents of a reagent LEWIS G0TTS,P"lma"y m selected from the group which consists of N-haloimides, LOVE, Assistant Examiner 

